1. Field of the Invention
The present invention relates to a metal complex of a fluorinated tin oxide and a titanium oxide, and a preparation method thereof.
2. Discussion of Related Art
In recent years, since energy consumption has been rapidly increasing worldwide, demand and supply of fossil energy has been unstable. For a stable supply of energy, various energy conversion technologies have been actively studied. In order to replace fossil fuel, alternative energy technology is currently under development. However, since people are heavily dependent on fossil fuels, a use of the fossil fuels is not expected to be decreased for a long time. Therefore, studies on production and a use of hydrogen by converting or reforming the conventional fossil fuels such as oil or coal have been carried out. Hydrogen energy is clean energy that does not produce carbon dioxide by combustion and can be readily used in many households along with development of reforming reactors capable of reforming the conventional gas to produce hydrogen. The hydrogen energy can be used not only for general combustion but also as a fuel gas for a fuel cell. A representative method of producing such hydrogen uses a methane-steam reforming reaction and a water-gas shift reaction. In the methane-steam reforming reaction, methane is reacted with steam at 600 to 800° C. in the presence of a nickel catalyst to produce hydrogen and carbon monoxide, and in the water-gas shift reaction, carbon monoxide produced from the downstream of a methane-steam reforming reactor is reacted again with steam to produce hydrogen and carbon dioxide. Typically, as a temperature of the water-gas shift reaction is increased, a reaction rate is increased but a conversion rate is decreased. On the contrary, as the temperature of the water-gas shift reaction is decreased, the reaction rate is decreased but the conversion rate is increased. Therefore, the water-gas shift reaction is composed of two steps: a high temperature water-gas shift reaction carried out at about 400° C.; and a low temperature water-gas shift reaction carried out at about 200° C. If a reaction rate of the low temperature water-gas shift reaction is increased, there is no need to carry out the conventional two-step water-gas shift reaction. Therefore, a recent trend of the study is focusing on development of a low temperature water-gas shift reaction catalyst capable of increasing the reaction rate.
As a conventional low temperature water-gas shift reaction catalyst, a Cu/ZnO/Al2O3-based oxide catalyst has been mainly used. Further, catalysts prepared by immersing Pt, Pd, Cu, Ni, or the like in ceria (CeO2) carriers having high oxygen mobility and a high oxygen storage capacity have shown excellent activity and thus have attracted a lot of attention. According to Korean Patent Laid-open Publication No. 2010-0089316, it is reported that binary active metals, Cu and Mo, are immersed at a certain content ratio in a ceria-zirconia (Cex—Zr1-xO2) carrier, so that it is possible to maintain high catalyst activity and also obtain high durability against thermal cycling at 250° C. or more as compared with a Cu-based catalyst or other conventional catalysts commonly used.